Bond- and Energy-Selective Carbon Abstraction from D-Ribose by Hyperthermal Nitrogen Ions

Electron attachment to fluorodeoxyglucose: Dissociation dynamics in a molecule of near-zero electron affinity

Fluorodeoxyglucose (FDG) is a glucose derivative with fluorine at the C₂ position. The molecule containing the radioactive F-18 isotope is well known from its application in positron emission tomography as a radiotracer in tumor examination. In the stable form with the F-19 isotope, FDG was proposed as a potential radiosensitizer. Since reduction processes may be relevant in radiosensitization, we investigated low-energy electron attachment to FDG with a crossed electron-molecule beam experiment and with quantum chemical calculations as well as molecular dynamics at elevated temperatures to reveal statistical dissociation. We experimentally find that the susceptibility of FDG to low-energy electrons is relatively low. The calculations indicate that upon attachment of an electron with a kinetic energy of ∼0 eV, only dipole-bound states are accessible, which agrees with the weak ion yields observed in the experiment. The temporary negative ions formed upon electron attachment to FDG may decay by a large variety of dissociation reactions. The major fragmentation channels include H₂O, HF, and H₂ dissociation, accompanied by ring opening.

Direct Hydrogenation of Dinitrogen and Dioxygen via Eley-Rideal Reactions

Most Eley-Rideal abstraction reactions involve an energetic gas-phase atom reacting directly with a surface adsorbate to form a molecular product. Molecular projectiles are generally less reactive, may dissociate upon collision with the surface, and thus more difficult to prove that they can participate intact in abstraction reactions. Here we provide experimental evidence for direct reactions occurring between molecular N2 (+) and O2 (+) projectiles and surface-adsorbed D atoms in two steps: first, the two atoms of the diatomic molecule undergo consecutive collisions with a metal surface atom without bond rupture; and second, the rebounding molecule abstracts a surface D atom to form N2 D and O2 D intermediates, respectively, detected as ions. The kinematics of the collisional interaction confirms product formation by an Eley-Rideal reaction mechanism and accounts for inelastic energy losses commensurate with surface re-ionization. Such energetic hydrogenation of dinitrogen may provide facile activation of its triple bond as a first step towards bond cleavage.